Making EuO multiferroic by epitaxial strain engineering

Veronica Goian, Rainer Held, Eric Bousquet, Yakun Yuan, Alexander Melville, Hua Zhou, Venkatraman Gopalan, Phillipe Ghosez, Nicola A. Spaldin, Darrell G. Schlom, Stanislav Kamba

Research output: Contribution to journalArticlepeer-review

21 Scopus citations

Abstract

Multiferroics are materials exhibiting the coexistence of ferroelectricity and ideally ferromagnetism. Unfortunately, most known magnetoelectric multiferroics combine ferroelectricity with antiferromagnetism or with weak ferromagnetism. Here, following previous theoretical predictions, we provide clear experimental indications that ferroelectricity can be induced by epitaxial tensile strain in the ferromagnetic simple binary oxide EuO. We investigate the ferroelectric phase transition using infrared reflectance spectroscopy, finding that the frequency of the soft optical phonon reduces with increasing tensile strain and decreasing temperature. We observe such a soft mode anomaly at 100 K in (EuO)2/(BaO)2 superlattices grown epitaxially on (LaAlO3)0.29-(SrAl1/2Ta1/2O3)0.71 substrates, which is a typical signature for a displacive ferroelectric phase transition. The EuO in this superlattice is nominally subjected to 6.4% biaxial tensile strain, i.e., 50% more than believed needed from previously published calculations. We interpret our results with new first-principles density functional calculations using a hybrid functional, which provides a better quantitative agreement with experiment than the previously used local-density approximation and generalized gradient approximation functionals.

Original languageEnglish (US)
Article number74
JournalCommunications Materials
Volume1
Issue number1
DOIs
StatePublished - Dec 2020

All Science Journal Classification (ASJC) codes

  • General Materials Science
  • Mechanics of Materials

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